New cases reported in multi-year, multi-country Salmonella outbreak

The increase in Salmonella Stanley cases in the country this year is suspected to be associated with the same turkey fattening and slaughtering facility in Hungary, previously implicated with cases in Austria in 2014, according to the European Centre for Disease Prevention and Control (ECDC).

The pulsed field gel electrophoresis (PFGE) pattern reported in 2015 in Austria and five other EU Member States is indistinguishable from strains associated with outbreaks and clusters from 2012 to 2014.

Germany, Hungary, Luxembourg, the Netherlands and Slovenia also uploaded isolates to the European Surveillance System (TESSy) with an indistinguishable profile from the outbreak strain and PFGE results for two additional countries are pending.

Outbreak strain still circulating​

“​These different pieces of information suggest that the strain causing outbreaks and clusters in previous years is still circulating and that additional sporadic or cluster cases are to be expected,” ​said ECDC.

“…ECDC and EFSA recommend that further actions should be taken by risk managers in countries to detect and contain S. Stanley infections in the turkey production chain, thus avoiding the subsequent contamination of turkey meat.” ​

An ECDC and EFSA assessment last year​ said 710 cases of non-travel-related S. Stanley infections were identified in 10 EU Member States between August 2011 and January 2013.

Between January and 8 October 2015, 141 cases of S. Stanley were identified in eight of the nine Austrian provinces, with the highest number reported in Upper Austria (55) and Tyrol (46), said the Austrian Ministry of Health and the Austrian Agency for Health and Food Safety (AGES).

The age of the cases range from four months to 81 years and 95 (67%) are male with hospitalisation reported for 45 cases.

Eighty were part of three clusters defined by time and place (one in January, one from April to June in Upper Austria, and one in July and August in Tirol).

Hungarian link again​

Descriptive epidemiology and microbiological investigation strongly suggested turkey kebab as the source of at least 36 cases.

Traceback analyses by national authorities identified the implicated turkey meat distributed in the two outlets in Upper Austria and one in Tirol had been supplied by a single food retailer in Slovakia.

Meat of the Slovakian retailer was suspected to originate from a turkey fattening and slaughtering facility in Hungary already involved in an Austrian S. Stanley cluster in 2014.

PFGE analysis of the isolates from outbreak cases showed indistinguishable profiles from the strain having caused the multi-country outbreak of S. Stanley infections in the European Union from August 2011 to January 2013​, and clusters of cases in 2013 and 2014.

From 2007 to 2014, the proportion of isolates resistant to nalidixic acid among S. Stanley cases increased from 10% in 2010 to 68% in 2011, and continued to increase up to 90% in 2014.

The proportion of isolates resistant to nalidixic acid and ciprofloxacin was low (range 1-17%) until 2014 when it reached 77.9%.

Variation in ciprofloxacin resistance should be interpreted with caution due to changes in EUCAST recommendations on antimicrobial testing and clinical break-points. The 2015 strains are resistant to nalidixic acid and exhibit low-level resistance to ciprofloxacin. 

The 2011-2012 outbreak strain was resistant to nalidixic acid only, however considering the revision of the EUCAST recommendations, the resistance pattern can be considered identical.